The first objective is to determine the relationship between cholecystectomy rates and characteristics of patients and of the medical groups where they receive care in a large medical care plan. In addition, the number of patients receiving surgical or medical treatment for gallbladder disease in a 3 to 4 year period after their diagnosis would be determined, primarily to assess the feasibility of an intensive, prospective study of the factors related to treatment and prognosis of gallbladder disease. The study would utilize the records of the Health Insurance Plan of Greater New York - hospitalizations for cholecystectomies, surgical reports, gallbladder x-rays and medical records of patients with such x-rays. Population characteristics of the HIP members in each medical group and characteristics of the medical groups are available to calculate cholecystectomy rates and their relationship to factors of interest. The numbers of gallbladder patients who are treated by surgery or not in a period after their diagnosis would be determined by examining x-ray reports, and surgical records.